Chemistry Reference
In-Depth Information
Fig. 30 Phase diagram for a
moderately incompatible
polymer pair and a solvent of
moderate quality that
dissolves polymer A and
polymer B equally well.
Open
symbols
composition of
coexisting phases,
closed
symbol
critical point,
shaded
area
unstable region [
27
]
N
1
=
1
0.00
1.00
0.25
0.75
0.50
0.50
0.75
0.25
1.00
0.00
0.00
0.25
0.50
a = 0.0025
z
= 0
0.75
1.00
N
A
=
1000
N
B
=
2000
CH
Fig. 31 Phase diagram of the
CH/branched PI/linear PI
system at 25
C obtained by
mapping homogeneous (
open
symbols
) and inhomogeneous
(
closed symbols
) mixtures.
The
M
w
of the linear polymer
is 21.6 kg/mol and that of the
branched material is 18 kg/
mol. The two phase region is
hatched
[
71
]
0.00
1.00
0.25
0.75
25°C
0.50
0.50
0.75
0.25
1.00
0.00
0.00
0.25
0.50
0.75
1.00
W
linear PI
PI
branched
PI
linear
Cosolvency
According to model calculations, the phenomenon of cosolvency should also occur
for solutions of polymer blends in a common solvent. For the example shown in
Fig.
32
, the components of the blend were chosen to be highly incompatible, and the
solvent to be bad for polymer B but favorable for polymer A.
